Download Reproductive System

Reproductive System
Chapter 22
Introduction
• Both male and female reproductive systems
function to produce and nurture sex cells
(gametes)
• Males- sperm
• Females- eggs/oocytes
Gametes
• Most human cells have 46 chromosomes
– Two each of chromosomes 1-22
– Sex chromosomes- XX female, XY male
• Sperm/egg have 23 chromosomes each
• Fertilization- joining of one egg and one sperm
= 46 chromosomes
Meiosis
• Producing gametes
Egg/sperm
Sex determination
• Females can only give an X to her offspring
• Males can give either an X or a Y
Male reproductive system
• Primary sex organs (gonads)- testes
• Accessory sex organs- internal and external
Male reproductive system
Organs
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Testes, scrotum- sperm and T
Epididymis- maturation
Vas deferens- storage
Urethra- travel through
Accessory glands- seminal fluid production
Penis- ejaculates sperm
Testes
• Paired structures within scrotum
• Sperm production
• Seminiferous tubules
– Site of production, contains
spermatogenic cells
• Interstitial (Leydig) cells
– Between tubules
– Secrete testosterone
Regulation of testes by anterior pituitary and hypothalamus
(LH and FSH) – causes secretion of testosterone and sperm
production
Puberty
• T levels increase
• Maturation of sperm
• Secondary sex characteristics
– Larynx enlarges, vocal folds thicken
– Muscle/bone development
– Facial, pubic hair
Anabolic steroids
• Drugs that have similar effects to testosterone
• Increase primary and secondary sexual
characteristics in the short term
• Watch Ben Affleck have a ‘roid meltdown (1994):
http://www.youtube.com/watch?v=3FvlIwuQBO8
Epididymis/Vas deferens
• Epididymis
– Coiled tubes on top of testes
– Maturation of sperm
• Vas deferens
– Muscular tubes for transporting sperm
Accessory glands
• Produce other components of semen (semen is
not just sperm!)
Seminal vesiclesenzymes, nutrients
(fructose), neutralizes
vaginal secretions
Prostate glandenzymes, neutralizing
fluid, help with sperm
motility
Bulbourethral glandlubricates, neutralizing
fluid (urine)
Penis
• Multi-functional
• Sensory nerves convey pleasure
Erection
BP treatment
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Female reproductive system
Female reproductive organs
• Primary (gonads)- ovaries
• Accessory organs- internal and external
• All organs specialized to
– Produce gametes
– Favorable environment for fetal development
– Produce sex hormones
Organs
• Ovaries- produce eggs (at birth), hormones
(estrogen/progesterone)
• Uterine (fallopian) tube- egg passes through,
fertilization
• Uterus- site of fetal development
• Vagina- receives sperm
Ovaries
• Paired structure
• Cortex- compact tissue, contains masses of
cells (ovarian follicles)
Uterine (fallopian) tubes
• Infundibulum with fimbriae
• Cilia assist in transport of egg
• Fertilization
Uterus
• Hollow, muscular
structure
• Site of fetal
development
• Layered
Lumen
Endometrium
Myometrium
Perimetrium
External organs
• Protection
• Pleasure
Gamete production
• Monthly cycle
– Follicular phase- follicle growth in the ovary
– Ovulation phase- ovary releases egg
– Luteal phase- corpus luteum secretes hormones
to prepare for pregnancy
• Alternates between ovaries
Follicular Phase
• Females are born with underdeveloped eggs,
lifetime supply
• FSH stimulates production of a follicle in the
ovary
• Follicle is basically a ball of cells that contains
the egg
Ovulation
• Follicle begins secreting estrogen
• Positive feedback, increases LH (outside of ovulation,
estrogen typically suppresses LH)
• LH surge causes release of egg
Luteal Phase
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•
•
•
2-5 cm in diameter!
Produces progesterone
Progesterone preps uterus for implantation
Lasts for 14 days, if no implantation
If implantation occurs, the implanted embryo secretes a
hormone that tells the corpus luteum to keep producing
progesterone
• Progesterone inhibits LH
The uterus
• Has a cycle that corresponds with the ovarian
cycle
• ~28 day cycle, day 1 of cycle corresponds with
first day of period
– Menses- sloughing off of endometrial lining
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Ovarian activity
Plasma hormonal
concentration
LH
FSH
FSH
Developing
follicle
LH
Early
corpus luteum
Mature
follicle
Regressive
corpus luteum
Ovarian events
Follicular phase
7
Days 1
Ovulation
14
Corpus
albicans
28
Luteal phase
21
Uterine activity
Estrogens
Progesterone
Plasma hormonal
concentration
Progesterone
Estrogens
Thickness
of endometrium
Days 1
3
5
Menstruation
7
9
11
13
Proliferative phase
15
17
19
21
23
Secretory phase
25
27
1
3
Menstruation
38
Birth control pills prevent pregnancy by maintaining high
levels of estrogen and progesterone, which inhibit pituitary
gland hormones and mimics pregnancy
Several methods of birth control
Fertilization
• https://www.youtube.com/watch?v=_5OvgQW6FG4
Fertilization/Implantation
Assisted Reproductive Technology (ART)
• Pregnancy via artificial means
• Infertility affects 1 in 7 couples
• Ranges from medications to lengthy procedures such as in
vitro fertilization (IVF)